Conventional fluid flow sensors often are used to sense the flow of a liquid. However, such sensors are generally designed to operate with a particular type of fluid, and are not always suitable for monitoring the flow of unknown fluids or mixtures (e.g., oil and water). Conventional sensors are intended for relatively steady state operation and may not be suitable for the dynamic flow produced by a pumpjack, where the flow comes in surges. One aspect of the venturi design was intentionally avoiding issues associated with sensors that rely on a spinning wheel or rotor to detect flow, while avoiding the cost of acoustic or magnetic sensors. Moreover, capacitive sensors are known to monitor the dielectric strength of the material between the sensors, thereby allowing for the characterization of the flowing fluid.
While fluid sensor technology may be known, there remains a need for a sensor suitable for detecting both a fluid flow rate and the dielectric strength of the flowing fluid. The dielectric strength can be employed to characterize the type of fluid, so that in combination it may be possible to determine the flow rates of different fluids that may pass through the sensor.
In one application contemplated for the disclosed embodiments, the fluid sensor may be used in a pumpjack production well, where oil, water and gas are present and may be extracted. The sensor is potentially able to detect each of three possible phases of the well's production, and to totalize the amount of water and oil produced from the well. And, the specific combination of components disclosed herein also allows for compaction and miniaturization, where an existing well may lack space for a long compound assembly to sense fluid flow and pressure.
Disclosed in embodiments herein is a fluid sensor comprising: a 2-dimensional venturi producing a controlled thickness of non-stratified fluid flow therethrough; a first fluid pressure sensor located on an inlet to the venturi; a second fluid pressure sensor located on an outlet of the venturi; a capacitive sensor located adjacent the 2-dimensional venturi, the capacitive sensor including a pair of parallel conductive metal plates located on each side of the 2-dimensional venturi.
Further disclosed in embodiments herein is a pumpjack monitoring and control system, including: an in-line fluid sensor, operatively coupled to receive the fluid output of a pumpjack connected to a wellhead, and to generate pressure and capacitance signals in response to the fluid output, said fluid sensor comprising, a) a first fluid pressure sensor located on an inlet to the venturi; b) a second fluid pressure sensor located on an outlet of the venturi; c) a capacitive sensor located adjacent the 2-dimensional venturi, the capacitive sensor including a pair of parallel conductive metal plates located on each side of the 2-dimensional venturi; and a controller, operating in accordance with a set of pre-programmed instructions, said controller receiving output from said fluid sensor, said controller processing the output and using said output to monitor the pumpjack output and to report the performance of the pumpjack, and to totalize the amount of oil and/or water pumped from the wellhead.
The various embodiments described herein are not intended to limit the disclosure to those embodiments described. On the contrary, the intent is to cover all alternatives, modifications, and equivalents as may be included within the spirit and scope of the various embodiments and equivalents set forth. For a general understanding, reference is made to the drawings. In the drawings, like references have been used throughout to designate identical or similar elements. It is also noted that the drawings may not have been drawn to scale and that certain regions may have been purposely drawn disproportionately so that the features and aspects could be properly depicted.